Diperoxoic acids are useful as bleaching agents, oxidizing agents, disinfecting agents, and the like.
Methods of preparing various classes of diperoxoic acid are known. U.S. Pat. No. 2,377,038 issued May 29, 1945 to J. S. Reichert et al discloses a process for preparing organic peracid by reacting an anhydride of a carboxylic acid and an alkaline solution of an inorganic peroxygen compound in an aqueous medium at a pH of 8.0-11.0. U.S. Pat. No. 2,813,896 issued Nov. 19, 1957 to K. Krimm discloses a process for preparing organic peracids by reacting monocarboxylic and dicarboxylic aliphatic, cycloaliphatic and aromatic acids and acid anhydrides with aqueous hydrogen peroxide solution in sulfuric acid using such amounts that H.sub.2 SO.sub.4 and H.sub.2 O are at the rate of at least 1 mole to 6 moles at the end of the reaction. U.S. Pat. No. 3,655,738 issued Apr. 11, 1972 to D. R. Nelson discloses the preparation of diperphthalic acids by the reaction of phthalic acid in the form of finely divided particles having a dimension below 0.1 millimeter and hydrogen peroxide in an alkane sulfonic acid medium. U.S. Pat. No. 4,172,086 issued Oct. 23, 1978 to S. Berkowitz discloses an improved process for the manufacture of a peroxycarboxylic acid prepared by the oxidation of a fatty acid with an excess of hydrogen peroxide in the presence of a strong acid catalyst by intimately dispersing throughout the reaction mixture a sufficient amount of an inert, water-immiscible solvent for the peroxycarboxylic acid to selectively remove from the aqueous phase the peroxycarboxylic acid as it is formed. U.S. Pat. No. 4,233,235 issued Nov. 11, 1980 to J. B. Camden et al discloses a process for making aliphatic diperoxyacids having 8 to 16 carbon atoms by continuously adding a dibasic acid of the formula HOOC -(CH.sub.2).sub.n - COOH, sulfuric acid, hydrogen peroxide and water to a reactor and continuously withdrawing the diperoxyacid formed to maintain a constant resident time for the reactants in the reactor. Similarly, U.S. Pat. No. 4,244,884 issued Jan. 13, 1981 to J. P. Hutchins et al relates to Camden et al and discloses a continuous process with two recycling loops.
U.S. application Ser. No. 490,591 filed on May 2, 1983 by J. M. Mayer, said application being owned by the owner of the present application, discloses substituted-butanediperoxoic acid bleaching agents. The preparation of the substituted butanediperoxoic acids shown in Ser. No. 490,591 is by the addition of hydrogen peroxide to a stirred mixture of substituted succinic anhydride and methanesulfonic acid. U.S. application Ser. No. 531,103 filed on Sept. 12, 1983 by H. R. Alul, also owned by the owner of the present application, discloses a process for making substituted-butanediperoxoic acids by reacting substituted succinic anhydride with a mixture of concentrated sulfuric acid and hydrogen peroxide.
Although these methods of preparing substituted-butanediperoxoic acids are effective it has now been found that these processes suffer the disadvantage of forming fine crystals of the substituted-butanediperoxoic acid product which gels the reaction mixture. The formed gel requires substantial increase in energy to agitate the reaction mixture, an increase in reactor size to accomodate the increased volume of the gel and prolonged production and product recovery periods. It has now been found that these disadvantages are overcome by using a reaction modifier.